Analysis of SLC4A11, ZEB1, LOXHD1, COL8A2 and TCF4 gene sequences in a multi-generational family with late-onset Fuchs corneal dystrophy

The aim of the present study was to determine the genetic basis of a multi-generational family with late-onset (LO) Fuchs corneal dystrophy (FCD). Five FCD causal genes [solute carrier family 4, sodium borate transporter, member 11 (SLC4A11), zinc finger E-box binding homeobox 1 (ZEB1), lipoxygenase homology domains 1 (LOXHD1), collagen, type VIII, alpha 2 (COL8A2) and transcription factor 4 (TCF4)], previously reported to be implicated in the pathogenesis of FCD, were screened. A total of 27 variants [including 22 known single nucleotide polymorphisms (SNPs) from the Single Nucleotide Polymorphism Database (dbSNP) and 5 variants absent from dbSNP] were detected in this FCD pedigree across the SLC4A11, ZEB1, LOXHD1 and COL8A2 genes as follows: i) 22 known SNPs from dbSNP, including 3 coding (p.R161R, p.S213S and p.T833T) and 11 non-coding variants of SLC4A11, 2 intronic SNPs of ZEB1 from dbSNP (rs220057 and rs220060), 1 intronic SNP of LOXHD1 from dbSNP (rs16939650), and 5 SNPs of COL8A2 from dbSNP (p.A35A, p.R155Q, p.L335L, p.G495G and p.T502M); and ii) 5 variants that have not been previously reported in FCD patients and that are absent from dbSNP were identified across the ZEB1 and LOXHD1 genes; these included 3 continuous indels located at the junction of the 5'-UTR and the adjacent exon 1 of ZEB1 [Indel 1 (c.-86_-53delins gggaggggtggaggcggaggggtGGGGGGGAAGG); Indel 2 (c.-52_-46delinsGGGAGGG); and Indel 3 (c.-45_-42delinsAGGG)], and 2 intronic variants of LOXHD1 (c.5332-126C>T and c.1809+155G>A). Apart from one intronic SNP of SLC4A11 from dbSNP (rs372201212), the pathologic consequence of which is uncertain, and 2 intron variants of LOXHD1 (c.5332-126C>T and c.1809+155G>A); the variants likely represent examples of de novo mutations. Neither of the other 24 variants provided strong evidence of pathogenesis in this FCD pedigree. An analysis of 7 SNPs in TCF4 from dbSNP, which have been associated with LO FCD in different populations, revealed that these 7 SNPs were not associated with FCD in this specific pedigree. A genome‑wide linkage scan to search for linkage to one of the previously described FCD loci or to identify a novel locus for FCD will need to be performed in this FCD pedigree. Our observation, nevertheless, expands the knowledge of the genetic status of patients with FCD.